1. Field of the Invention
The present invention relates to a printing apparatus particularly but not exclusively adapted to apply a layer of viscous sticky material, particularly varnish, in the form of a pattern or otherwise, to a substrate comprising an applicator roll and means for applying the viscous material to said roll, the substrate being fed by feed means between the applicator roll and an impression roll in order to take up the viscous material.
2. Description of the Prior Art
In the prior art apparatus for applying a varnish in a pattern or otherwise to a substrate has been used, in the form of a gravure roll to which the varnish is fed and then skimmed off by a squeegee device. The varnish is then transferred from the gravure roll to the applicator roll and from there to the substrate material. This action has proved to be detrimental, as varnish consists of a viscous and sticky substance, and tends to stick in the grooves of the gravure roll. This occurs particularly when a relatively thick layer has to be applied to the substrate material and the grooves of the gravure roll are correspondingly deep.
Even if varnish is to be applied without a pattern and accordingly a smooth applicator roll is used, the drawback arises that it is difficult to apply a uniformly thick layer of varnish to said applicator roll so that there again only one thin layer of varnish can be applied on each treatment.